Thermally released closer for fire doors



M OO

June 19, 1962 c. F. GERHARDT 3,039,573

THERMALLY RELEASED CLOSER FOR FIRE DOORS Filed NOV. 9. 1959 2 Sheets-Sheet 1 'CariFGarh i yfi O a MQW Q QM ATTORNEYS J1me 1962 c. F. GERHARDT THERMALLY RELEASED CLOSER FOR FIRE DOORS 2 Sheets-Sheet 2 Filed Nov. 9, 1959 lNV EN TOR CarlJTGarhardf,

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BY Q and ATTORNEYS.

United States Patent 3,039,573 THERMALLY RELEASED CLQSER FOR FIRE DOORS Carl F. Gerhardt, Kenmore, N.Y., assignor to Dusing and Hunt, Inc., Buffalo, NY. Filed Nov. 9, 1959, Ser. No. 851,843 2 Claims. (Cl.18947) This invention relates to thermally released mechanism for automatically closing fire doors and the like upon the occurrence of fire.

Thermally operated means for closing fire doors in the event of a fire have been employed heretofore. The present invention provides improved means for this general purpose. According to the present invention a mechanism is provided which is normally inactive and which in the event of a fire engages and cooperates with other means to close the door. Such other means comprises a resilient arrangement which normally acts against frictional forces to assist in normal door closing operations. Fire doors of the type contemplated herein are usually, although not necessarily, of the sliding type.

The present invention provides a generally selfcontained door closing mechanism in which spring means is arranged to be stressed during door opening movements but to a degree less than the frictional forces involved, so that the door remains open under normal conditions. The force of the spring means assists in door closing movement and, when the thermal closing means comes into operation, adds its force to the thermally operated closing means.

Accordingly, the additional force of the thermally operated closing means necessary to effect emergency door closing operation is considerably less than would otherwise be the case. In the specific instance set forth herein by way of example, the thermally released door closing motive means comprises a weight and pulley arrangement and the weight merely augments the aforesaid spring force to a degree sufiicient to effect certain closing of the door in the event of a fire.

The thermal door closing mechanism is normally entirely inactive so as not to interfere with normal everyday door opening and closing movements and is generally contained within a single unitary casing so that its readiness for emergency use in the event of a fire is not apt to be lessened despite the long periods which usually elapse before such emergency closing mechanism comes into action.

A single specific embodiment of the principles of the present invention is illustrated in the accompanying drawings and described in detail in the following specification but it is to be understood that such embodiment is merely by way of example and that various modifications and mechanical variations may be introduced without departing from the spirit of the invention and the scope thereof is not limited excepting as defined in the appended claims.

In the drawings:

FIG. 1 is a general elevational view of a door opening and a sliding fire door therefor provided with one form of the thermally actuated door closing means of the present invention;

FIG. 2 is a cross-sectional view on the line II--II of FIG. 1 on a considerably enlarged scale;

FIG. 3 is an elevational view of the mechanism of FIG. 2 viewed as in FIG. 1 but on approximately the same scale as FIG. 2 and with the cover of the casing removed to illustrate the internal mechanism; and

FIG. 4 is a cross-sectional view taken generally on the line IV-IV of FIG. 2.

Like characters of reference denote like parts in the several figures of the drawings and, referring to FIG. 1, the numeral designates a door opening in a building Wall and the numeral 11 designates a generally conventional sliding fire door which is guided for sliding opening and closing movements with respect to the door opening 10 by conventional means not shown.

The door closing mechanism of the present invention is generally disposed within a casing 13 having an outer cover member 14. As best shown in FIG. 2, casing 13 need have only a partial rear wall 15 which includes a bearing 17 for a shaft 18 which supports the operating parts of the door closing mechanism.

Shaft 18 is free to rotate in bearing 17 but is normally restrained against such rotation by a pin 20 which projects through the bearing 17 and shaft 18 in the position shown in FIG. 2 but may be raised by means of a manipulating upper end portion 21 to free the shaft for rotation relative to the bearing 17 for purposes of adjustment, as will appear later herein.

An annular casing 22 is rotatable on shaft 18 and con- I tains a flat spiral torsion spring 23 of the clock spring type which is fixed at its inner end to shaft 18 as at 24 and is fixed at its outer end to the outer portion of casing 22. A reel or sheave 25 is likewise rotatably mounted on shaft 18 and includes a laterally projecting pin 26 near its outer periphery which extends into an opening in casing 22, whereby reel 25 and casing 22 are normally held for joint rotation.

A cable 27 which is wound upon reel 25 is attached at one end to the reel and at its other end to door 11 as at 28. From this much, it will be seen that opening movement of sliding door 11 unwinds cable 27 and jointly rotates reel 25 and casing 22 to stress the torsion spring 23. The tension of torsion spring 23 is arranged to be only enough to almost overcome the friction of the sliding movement of door 11.

Thus when the door is in an open position it will remain open by friction but spring 23 counterbalances most of the friction so that the door can be closed by a fairly light additional force, either manually or by the automatic door closing mechanism of the present invention.

The initial tension of torsion spring 23 can readily be adjusted by raising the pin 20 to release the same, rotating the shaft 18 to wind the spring, then replacing the pin 20 in its locking position. The outer end of shaft 18 is provided with a wrench receiving formation as at 30 to facilitate such adjustment. The foregoing parts are the only ones which enter into door operation excepting under fire conditions.

The thermally actuated closing mechanism of the present invention will now be described. A cable reel or drum 3-1 is mounted on shaft 18 adjacent to reel 25 but normally spaced therefrom. A cable 32 wound upon drum 31 has a Weight 33 attached to its lower depending end and is attached at its opposite end to drum 31 so that it biases the same for rotation in a clockwise direction, as viewed in FIGS. 1, 3 and 4. v

The bias of Weight 33 on drum 31 is normally rendered inoperative by a restraining Wire or cable 35 which is attached at one end to the building, as at 36, and in the present instance passes over a peg 37 and leads to a connecting pin 38. The lower end of connecting pin 38 is return bent as at 39 and an eyelet formation 40 at the end of cable 35 slips over this return bent portion.

The inner end of pin 38 has a slip-fit in a collar 41 which is attached to the hub of drum 31 but pin 38 is held against dropping therefrom by the cocking resulting from the tension of cable 35 against the lower end of pin 38. A pair of fusible devices are shown at 43 and 44 in FIG. 1 and if fire or abnormal heat conditions cause either of the elements 43 or 44 to melt or part, the pull of cable 35 on drum 31 will cease and the weight 33 will be free to rotate the drum.

The hub of drum 31 is provided with a screw 45. The

inner end of this screw rides in a groove formation in shaft 18. This groove formation comprises a fully annular peripheral groove portion 47 and an oblique groove portion 48 which merges therewith. When reel 31 is in the position shown in FIG. 2, with cable 35' intact, screw 45 projects into the oblique portion 48 of the groove and drum 31 is thereby held spaced from reel 25.

Drum 31 is provided With a pair of lateral clutching projections 59 and reel 25 is provided with a plurality of companion clutching projections 51. When drum 31 is held in its spaced position of FIG. 2 by the pull of the cable 35 which contains the fusible elements 43 and 44, screw 45 is in engagement with the oblique groove portion 48 of shaft 18 and the clutch parts 50 and 51 are axially spaced and do not interfere with free rotation of drum 25 in opening and closing movements of the door,

However, when ,the restraint of cable 35 is broken by release of one of the fusible elements 43' or 44 and weight 33 acts to rotate drum 31, screw 45 rides in oblique slot portion 48 and earns the drum 31 toward reel 25 to engage the clutch parts 50 and 51 and drum 31 continues to rotate under the impetus of Weight 33 with the end of screw 45 riding in the circular portion 47 of the groove in shaft 18, whereby reel 25 is rotated and winds cable 27 thereon to draw the door 11 thereto and thus close the same. It will be noted that this closing movement is augmented by the urge of torsion spring 23 so that positive closing of the door under emergency conditions requires only a relatively light assisting force on the part of reel 31 and weight 33.

I claim:

1. A thermally operated closing means for doors comprising a shaft and means. supporting the same, a reel rotata-bly mounted thereon and a cable from said reel to said door to close the latter upon cable winding rotation of said reel, a torsion spring acting between said shaft and said reel to bias the latter toward door closing position with a force less than required for door closing movement, force means carried by said shaft and fusible means normally restraining said force means, normally disengaged clutch means adapted to act between said force means and said reel, said force means being operable upon disruption of said fusible means to engage said clutch means and rotate said reel to close the door.

2. A thermally operated closing means for doors comprising a shaft and means supporting the same, a member rotatably mounted on said shaft and means acting between said member and said door to close the latter upon rotation of said member, a drive wheel rotatably mounted on said shaft and torque means for imparting a rotational driving force to said drive wheel, and fusible means normally restraining said drive wheel, normally disengaged clutch means adapted to act between said drive wheel and said rotatable member, said drive wheel being operable upon disruption of said fusible means to engage said clutch means and rotate said rotatable member to close the door.

References Cited in the file of this patent UNITED STATES PATENTS 570,710 Newhall Nov. 3, 1896 2,019,084 Miller Oct. 29, 1935 FOREIGN PATENTS 427,662 Great Britain Apr. 29, 1935 

